In article ,
Jeff Liebermann wrote:
Any ideas how to eliminate cross channel intermodulation with good antenna?
Or right antenna?
You're antenna isn't going to do much for removing excessively strong
signals, such as paging. The single best improvement you can do is to
lose your scanner, and get a better receiver with a better 3rd order
intermod (IMD3) specification. By the nature of the beast, scanners
are highly susceptible to intermod mixes in their front ends.
This is also a problem for many (most?) modern ham HTs, which have
broad-as-a-barn front ends. Their "DC to daylight" reception is both
a feature-advantage and a robustness-disadvantage. Older single-band
radios often have better front end filters.
There are cavity and crystal notch filters, that will reduce the
signal levels around the paging transmitter frequency, without
affecting the operating frequency (much). Search for crystal VHF
notch filter or cavity VHF notch filter.
http://www.parelectronics.com/amateur.php
I can offer a thumbs-up for the PAR Electronics VHFTN152-158. I had
terrible pager intermod problems with my Yaesu VX-5, whenever I had it
hooked to a "real" antenna (roof, bicycle-mobile flag J-pole, etc.)
rather than a rubber duck.
The pager-notch filter eliminated the problem, and as far as I can
tell it hasn't had a significant effect on ham-band receive
sensitivity or transmit power on either 2 meters or 440. I assume I'm
losing some signal and power due to insertion loss but it hasn't been
noticeable.
--
Dave Platt AE6EO
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